This invention relates generally to egg turning during incubation, and relates particularly to a portable, automatic egg turner, being especially adapted for use in still-air incubators, and to methods for continuous egg turning.
During egg incubation, it is known to be advantageous to shift in periodic manner the orientation of the incubating eggs to supply fresh albumen to the growing embryo within each egg and to produce proper muscular movement of the developing fowl inside the eggshell by avoiding sticking of the fowl to the eggshell. Incubators are provided with apparatus for supporting one or more tiers of egg trays and for rocking the egg trays back and forth in a see-saw-like motion.
Circulated air incubators are provided with means for circulating the atmosphere within the incubator to maintain evenness of air temperature. Still-air incubators are those not having air circulation means and because of their relative simplicity are compact and relatively economical. The fertile egg hatch rate associated with still-air incubators is generally significantly less than that associated with circulated air incubators, due in part to the impracticality of using egg turning apparatus within compact still-air incubators. The present invention is especially concerned with egg turning in still-air incubators.
Conventionally, automatic egg turners for incubators are actuated in an intermittent fashion, such that the drive means of the egg turner is intermittently activated to turn the eggs to one side and then deactivated so that the eggs are allowed to rest on that side, etc. Such intermittent egg turning is characterized by a time period of motion that is substantially less than the period of the overall turning cycle. To carry out this irregular motion during a turning cycle, automatic intermittent turners require additional apparatus for timing beyond that required for actual turning. Manually actuated egg turners are inherently intermittent for practical reasons. Various examples of intermittent egg turners are given in U.S. Pat. Nos. 2,625,906; 3,669,075; 2,782,759; 1,638,803; and 962,594.